Hello, i know that finasteride avoids the productions of dht by methods i cant explain with my bad english. The fact is that the DHT is needed for the erectile functions of the penis. How can i think that sex/masturbation dont make the body to produce more DHT to have reserves?

If that logic holds true, then all the bald men of the world must be sex addicts or rampant masturbators. Please excuse my humor, but your assumptions are erroneous. Increased DHT does not lead to erectile dysfunction. And increased sex or masturbation does not cause hair loss. Have fun!